Separation assembly for drug delivery device

ABSTRACT

A separation assembly for a container for separating a first component from a second component is disclosed. The separation assembly includes a generally cylindrical body that is constructed and arranged to be slidably supported within a container between a liquid component and a dry component. The body includes a seal structure constructed and arranged within the container between the first component and the second component. The seal structure has an inner seal member wherein the inner seal member is initially in a sealing condition that maintains the first component sealed from the second component. The inner seal member being converted to a mixing condition in response to the predetermined operating condition such that the first component flows through at least one flow path in the seal structure to mix with the second component. The body further includes a flow distributing member disposed adjacent the seal structure to evenly distribute the first component into the second component upon occurrence of the predetermined operating condition. The seal structure and the flow distributing member form a single unit.

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application is a divisional application of U.S. patent Ser.No. 09/897,422 filed on Jul. 3, 2001 which is related to provisionalapplication Nos. 60/238,458, 60/238,448, and 60/238,447, all filed onOct. 10, 2000, all under the title of “Wet/Dry Automatic InjectorAssembly,” and all of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to drug delivery devices fordelivering a medicament. In particular, the present invention isdirected to an automatic injector assembly for quickly combining twocomponents to form a liquid medicament, and delivering the liquidmedicament to an injection site.

[0004] 2. Description of Related Art

[0005] An automatic injector is a device that enables intramuscular (IM)or subcutaneous administration of a dosage of medicament. Generally, themedicament is stored as a liquid formulation which is then injectedintramuscularly. An advantage of automatic injectors is that theycontain a measured dosage of a liquid medicament in a sealed sterilecartridge. As such, automatic injectors allow for quick and simple IMinjection of a liquid medicament in emergency situations without theneed for measuring dosages. Another advantage of automatic injectors isthat the administration of the medicament is accomplished without theuser initially seeing the hypodermic needle through which the medicamentis delivered, and without requiring the user to manually force theneedle into the patient. This is particularly advantageous when themedicament is being self-administered.

[0006] There are drawbacks associated with the long-term storage ofmedicament in a liquid formulation. For instance, some medicaments arenot stable in solution and thus have a shorter shelf life than theirsolid counterparts. To address this concern, automatic injectors havebeen developed which store the medicament in solid form and mix thesolid medicament with a liquid solution immediately prior to injection.These injectors, disclosed for example in U.S. Reissue Pat. No. 35,986,entitled “Multiple Chamber Automatic Injector,” (the disclosure of whichis incorporated herein specifically by reference), however, require theuser of the injector to manually rupture a sealing member between thesolid and liquid components and then manually shake the injector body toexpedite dissolution of the solid component prior to injection. Thisincreases the time needed to administer a dose of the medicament.However, rapid delivery of the medicament is needed in many emergencymedical situations (e.g., nerve gas and chemical agent poisoning). Otherwet/dry injection devices have been expensive to manufacture or providedunsatisfactory mixing of components prior to injection. Therefore, thereis a need for a cost-effective automatic injector that stores medicamentin solid form that does not require manual premixing by the user.

SUMMARY OF THE INVENTION

[0007] In response to the foregoing challenges, applicants havedeveloped an innovative automatic injection device containing apre-loaded charge of medicament for automatically administering themedicament upon actuation thereof. The automatic injection devicecomprises a housing assembly and a chamber disposed within the housingassembly. The interior chamber includes a dry compartment for storing apredetermined charge of dry medicament therein, and a wet compartmentfor storing a predetermined amount of liquid injection solution therein.A seal structure is disposed to seal the dry compartment from the wetcompartment while the injection device is in storage. The seal structurepermits the liquid injection solution to pass there through and mix withthe dry medicament to form a medicament mixture within the chamberduring an injection operation. A needle assembly is in communicationwith the medicament mixture during the injection operation to enableadministration of the medicament mixture. A plunger is disposed withinthe chamber and is movable through the chamber during the injectionoperation to force the medicament mixture through the needle foradministration of the medicament mixture. A stored energy activationassembly is operable to release stored energy that forces the plungerthrough the chamber during the injection operation. The seal structureis conditionable in response to operation of the activation assembly topermit the liquid solution to pass therethrough and mix with the drymedicament as aforesaid.

[0008] Other aspects and advantages of the present invention will becomeapparent from the following detailed description, drawings and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The invention will be described in conjunction with the followingdrawing in which like reference numerals designate like elements andwherein:

[0010]FIG. 1 is a longitudinal cross-sectional view of a wet/dryautomatic injector assembly in accordance with an embodiment of thepresent invention.

[0011] FIGS. 2A-2B illustrate longitudinal cross-sectional views ofneedle support assemblies in accordance with certain embodiments of thepresent invention.

[0012] FIGS. 3A-3D illustrate cross-sectional side views of variouscartridge or chamber configurations and corresponding needle assemblyoptions according to certain embodiments of the present invention.

[0013]FIG. 4 is an enlarged partial cross-sectional side view of aneedle assembly/cartridge engagement according to the embodimentillustrated in FIG. 3A.

[0014] FIGS. 5A-5D illustrate cross-sectional side views of variousembodiments of a seal structure according to the present invention.

[0015]FIG. 6A is a longitudinal cross-sectional side view of a sealstructure in accordance with another embodiment of the presentinvention, wherein the movable sealing plug is in a closed sealingposition blocking the flow of the liquid injection solution.

[0016]FIG. 6B is a longitudinal cross sectional side view of sealstructure similar to 6A, but showing the movable sealing plug in an openby-pass position permitting the flow of the liquid injection solution.

[0017]FIG. 6C is a lateral cross sectional view of the seal structure ofthe present invention taken through the line 6C-6C in FIG. 6A.

[0018]FIG. 6D is a lateral cross sectional view of the seal structure ofthe present invention taken through the line 6D-6D in FIG. 6B.

[0019]FIG. 7 is a longitudinal cross-sectional view of a wet/dryautomatic injector cartridge or chamber configuration in accordance withanother embodiment of the present invention.

[0020]FIGS. 8A and 8B are longitudinal cross sectional views of twoadditional embodiments of seal structures in accordance with the presentinvention.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION

[0021] Referring now, more particularly to the figures, there is shownin FIG. 1 an automatic injector assembly 10 in accordance with anembodiment of the present invention. The present invention is describedin connection with a push button type auto injector, whereby the userremoves an end cap assembly and presses a button to trigger theinjection process. The present invention, however, is not limited topush button type automatic injectors; rather, it is contemplated thatthe present invention may be incorporated into a nose activated autoinjector, as described for example in U.S. Pat. No. 5,354,286, thedisclosure of which is hereby incorporated herein by reference for suchteaching.

[0022] The automatic injector assembly 10 includes a generally hollowtubular plastic housing 110. Generally, the housing 110 includes aninjection end 111 and an activation end 112, as shown in FIG. 1. In theembodiment shown, an actuator assembly 120 is inserted into the rearwardend of the housing 110. The actuator assembly 120 is received within thehousing 110 until flange 115 of a sleeve member 144 snaps into annulargroove 117 on the interior surface of housing 110. A removable safetycap 130 is releasably secured to the actuator assembly 120.

[0023] The actuator assembly 120 is of any conventional type as known inthe art, such as that disclosed in commonly assigned U.S. Pat. No.5,391,151 hereby incorporated by reference. The present inventionemploys a rear-end activating device, similar to that in theaforementioned U.S. Pat. No. 5,391,151, and is therefore only brieflydiscussed herein. The actuator assembly 120 includes an activationbutton sleeve 132 having internal activation surfaces 134. Theactivation assembly further includes a plastic collet 122 with a splitrearward portion forming spring fingers 136 as known in the art. Thesafety cap 130 has a pin portion 138 that extends between the springfingers 136 so as to keep them spread apart when the injector is in astorage condition. The spring fingers 136 terminate in semi-conicalconfigurations including rearwardly facing sloping surfaces 139 andforwardly facing flat surfaces 142. The collet 122 is surrounded by acylindrical sleeve 144 having inwardly extending flange 146 at therearward end thereof. The collet 122 has a forward annular flange 148. Acoil spring 250 surrounds the collet 122 and is compressed between theflange 148 and flange 146. The collet flat surfaces 142 are retained inengagement with the rearwardly facing surfaces of the flange 146, andthus prevented from moving off of the flange surfaces by the pin 138when the injector is stored.

[0024] To activate the injector, the safety pin 130 is manually pulledoff of the rear end of the injector, thus removing pin 138 from betweenthe fingers 136. The activation button 132 can then be pushed inwardly,and as a result of the activation surfaces thereof, 134 engages thesloping surfaces 139 of the spring fingers 136. This forces the springfingers 136 inwards toward one another and off of the retaining surfacesof the flange 146. The compressed spring 250 is then free to release thestored energy therein to move the collet 122 forwardly under the forceof the spring to affect an injection operation as will be describedlater in more detail.

[0025] It is contemplated that the actuator assembly 120 can be of anytype known in the automatic injector art that employs releasable storedenergy. For example, rather than emptying a spring, it may employ acharge of compressed gas.

[0026] Located within the interior of the housing 110 is a vial orchamber 150, preferably made of glass, for containing both the liquidinjection solution and the dry medicament. The chamber 150 is preferablya hollow cylinder, with a smooth cylindrical inner surface. The liquidinjection solution is located within a wet portion 151 of the chamber150. The dry medicament is located within a dry portion 152 of thechamber 150. It is contemplated that the dry medicament may be inpowder, lyophilized, freeze-dried, or any other solid formulation knownin the art. A seal structure 160 engages the interior side walls of thechamber 150 to seal the dry portion 152 from the wet portion 151 and toprevent seepage of the liquid injection solution into the dry portion152 prior to activation of the injector assembly. Further, a needleassembly 140 mounts to the forward end of vial or chamber 150 to injectthe medicament upon activation of the injector assembly. In thisembodiment, the forward end portion of the chamber 150 has an annulargroove 153 formed therein for attachment of the needle assembly 140. Theneedle assembly 140 includes a funnel-shaped needle support 143. Thewide end of the needle support 143 has an annular rib 145 that issnap-fit into groove 153 to form a seal with the chamber 150. The needlesupport 143 can be made of a resilient plastic material, or metal with arubber seal that seats into groove 153. The forward narrow end 147 (seeFIG. 2A) of the needle support 143 sealingly receives the rearward endof hollow needle 141. The needle support 143 forms a sealed fluidchannel from the chamber 150 to the needle 141. A rubber needle sheath202 surrounds the needle 141 and receives the narrow end 147 of theneedle support 143. A filter 190 is sealingly retained across the entirewide-end mouth of the needle support 143 by an annular sealing washer156.

[0027]FIGS. 2B, 3A, and 4 illustrate another embodiment of a needleassembly 140 and chamber 150. The chamber 150 in this embodiment isknown in the art as a dental cartridge. The dental cartridge has acylindrical rear portion and a narrowed forward neck portion defining anouter annular groove 153. The forward end of the dental cartridgedefines an annular flange portion 154. In this embodiment, the needlesupport 143 has a rearward annular flange 155 that receives an annularsealing member 156 that surrounds both sides of flange 155. The sealingmember 156 serves to seal a filter 190 over the wide end of the funnelshaped needle support 143. The rearward surface of the sealing member156 is sealingly clamped against the forward surface of chamber flange154 by a metal retaining clamp 157 as best seen in FIG. 4.

[0028] Returning to FIG. 1, forward end 1221 of the collet 122 extendsinto the rearward end of chamber 150 and is adapted to connect with aplunger 170 rearwardly sealing the wet container 151. The plunger 170 isadapted to sealingly engage the side wall of the wet container 150 toprevent leakage of the contents (e.g., liquid injection solution) of thewet container 151. The plunger 170 is preferably formed from a materialhaving low frictional properties such that the collet 122 and plunger170 may easily slide within the wet container 150 when operated.Alternatively, the plunger 170 may be lubricated with silicon or othersuitable non-reactive lubricant. The movement of the collet 122 and theplunger 170 pressurizes the liquid located within the wet container 151.A suitable medicament is located within a dry container 152.

[0029] The embodiment of FIGS. 1 and 2A is advantageous in that it hasan open mouth configuration wherein the needle-end of the vial orchamber is not significantly narrowed or tapered. Such an open mouthconfiguration permits direct access to the dry portion 152 of chamber150 for easy loading. Further, the open mouth configuration aids inpreventing cross contamination between wet portion 151 and dry portion152 in that the dry portion 152 does not have to be filled throughliquid portion 151 of chamber 150. Needle assembly 140 can be mounted tovial or chamber 150 in a snap-on configuration (FIG. 3B), an internalmount configuration (FIG. 3C), or an external needle assemblyconfiguration (FIG. 3D).

[0030] As mentioned above, the seal structure 160 is adapted to engagethe interior side walls of chamber 150 to prevent passage of thecontents (e.g., liquid injection solution) of wet portion 151 into thedry portion 152 prior to activation of the automatic injection assembly.Generally, seal structure 160 can include an outer sealing member 180, amovable sealing plug 166, a by-pass zone 165, at least one flow path167, and preferably also includes a filter or membrane 164. Withreference to FIGS. 5A-D, seal structure 160 can preferably be formed asa six piece (FIG. 5A), five piece (FIG. 5B), four piece (FIG. 5C), orthree piece (FIG. 5D) configuration.

[0031] More particularly, with reference to FIG. 5A, the outer sealingstructure 180 of the six piece configuration can comprise a two pieceannular rigid body 181 wherein members 181 a, 181 b thereof are formedinto the two piece rigid body using, e.g., annular weld connections orother bonding techniques known in the art. Outer sealing structure 180can further include multiple external sealing members 182, e.g., twoO-rings, to provide an annular sealing engagement with the inner wall ofvial or compartment 150. The sealing structure 180 further includes aninternal plug member 166 and a filter or dispersion membrane 164 as willbe discussed in greater detail later.

[0032] In another embodiment, as shown in FIG. 5B, rather than pluralO-rings, outer sealing structure 180 can include a single externalsealing member 182, e.g., a unitary gasket, to provide an annularsealing engagement with the inner wall of vial or compartment 150.External sealing member 182 may optionally be secured to two piece rigidbody 181 using any bonding techniques known in the art. Further, rigidbody members 181 a, 181 b may be shaped such that they securingly engageexternal sealing members 182 within notched recesses 183. Alternately,sealing members 182 may be secured to rigid body members 181 a, 181 b byan interference fit. As with the first embodiment, a filter or membrane164 is clamped in place at the proximal end of flow path 167 betweenmember 181 a and member 181 b of the two piece rigid body.

[0033] In another embodiment, as shown in FIG. 5C, outer sealingstructure 180 comprises a unitary internal rigid member 181 and anexternal sealing member 182. Again, internal rigid member 181 andexternal sealing member 182 may optionally be secured together using anybonding techniques known in the art. Further, internal rigid member 181and external sealing member 182 may be formed such that they securinglyengage each other using a combination of notched recesses 183 andextending shoulders 184. The filter or membrane 164 can be held in placebetween internal rigid member 181 and shoulder 184 of external sealingmember 182. In yet another embodiment, as shown in FIG. 5D, outersealing object 180 can comprise a unitary external sealing member 182which can optionally be molded so as to accommodate filter or member 164within retaining recess 185. FIGS. 6A and 6B illustrate anotherembodiment that is very similar to that of FIG. 5A, but provides aslightly different shape for outer annular rigid body 181 andparticularly the members 181 a, 181 b thereof.

[0034] In each embodiment illustrated in FIGS. 5A-5D and 6A-6B, externalsealing member 182 is preferably formed from a non-reactive elastomermaterial which can provide for the necessary sealing engagement with theinner wall of vial or compartment 150. Further, external sealing member182 can optionally be lubricated with silicon or other suitablenon-reaction lubricant to facilitate movement of the outer sealingobject 180 forwardly within vial or compartment 150 upon receivingsufficient force as will be described. The movable sealing plug 166 ispreferably formed from a material having low frictional properties suchthat the sealing plug 166 may easily slide within outer sealing object180 when the injector is activated. The movable sealing plug 166 mayalso optionally be lubricated with silicon or other suitablenon-reactive lubricant. In each of the embodiments illustrated, theouter annular structure 180 defines an inner surface having a smoothcylindrical configuration towards the rearward portion 169 thereof, andlongitudinally extending grooves 168 towards the forward portionthereof. The grooves 168 create a flowpath or flowpaths 167 throughwhich liquid in the wet compartment 151 can bypass seal plug 166 whenthe plug 166 is moved forwardly from sealing engagement with cylindricalsurface portion 169 into the grooved portion 168. The movement of thesealing plug 166 into the by-pass area 165 opens the fluid flow path 167between wet portion 151 and dry portion 152. The movable sealing plug166 preferably includes a plurality of circumferential grooves 186 toprovide for enhanced sealing engagement and to facilitate sliding actionof the plug 166.

[0035] As mentioned above, the seal structure 160 preferably includesfilter or membrane 164 at the end of flow path 167 through which theliquid injection solution may pass after the injector has beenactivated. The liquid injection solution then enters the dry portion 152of the chamber 150 where it mixes with and dissolves the dry medicament.More particularly, the filter 164 disperses the liquid injectionsolution exiting the seal structure 160 to present laminar fluid flow tothe full surface of the dry medicament, thereby wetting the entiresurface of the dry medicament for rapid and complete dissolution. Thefilter membrane 164 can be any structure that generally uniformlydistributes the liquid across the entire diameter of the chamber 150 forenhanced dissolution of the dry medicament.

[0036] During operation, manual activation of the actuator assembly 120releases the collet 122 (as described above), which applies pressure onthe plunger assembly 170. The application of pressure on the plungerassembly 170 by the collet and spring assembly 124 moves the plunger 170in the direction of the needle assembly 140. As a result, the entirechamber 150 and needle assembly 140 are moved forwardly in the housing110 such that needle 141 pierces through the front end of sheath 202 andexits through the forward end of the housing 110, and particularlythrough a hole 204 in the front nose-cone portion 206 of the housing.The sheath 202, which serves to maintain the needle 141 sterile when theinjector is in storage, also serves as a shock absorber duringactivation as it is compressed in generally accordion like fashionbetween the nose cone 206 and needle support 143.

[0037] When the needle 141 is extended from the housing 110 and thechamber 150 and needle support 143 approach the nose cone 206 portion ofthe housing so that further forward movement of chamber 150 issubstantially resisted, the plunger 170 then begins to travel forwardlythrough the chamber 150. This pressurizes the liquid injection solutionlocated within the wet compartment 151. With reference to FIGS. 6A-6B,the increased pressure within the wet compartment 151 moves the sealingplug 166 from a first sealed position wherein sealing plug 166 issealingly engaged with surface 169 of outer sealing structure 180 (FIG.6A) to a second by-pass position (FIG. 6B) that allows the injectionsolution to flow through flow path 167 created by grooves 168 andthereby through seal structure 160.

[0038] As described above, the high pressure developed within the wetportion 151 in response to movement of the collet 122 and the plungerassembly 170 forces the liquid injection solution through the sealstructure 160 dissolving the drug into a medicament injection solutionwhich will then be forced out through the needle 141 and into thepatient. As the collet 122 and plunger assembly 170 continue forward,the plunger 170 will eventually contact the seal structure 160, which,in a preferred embodiment, causes the seal structure 160 to move in thedirection of the needle assembly 140. Movement of the seal structure 160would cause any remaining solution within the portion 152 to bedispersed through the needle assembly 140, so as to reduce the amount ofresidual medicament remaining within the chamber 150.

[0039] Referring to FIGS. 2A, 2B and 4, a membrane or filter 190 ispreferably provided adjacent the needle assembly 140 to prevent any drymedicament particles from clogging the rearward end of needle 141 priorto an injection operation. The membrane 190 may also serve to slightlyrestrict or slow injection of medicament into the patient, to facilitatemore thorough dissolution during injection.

[0040] More particularly, to prevent the passage of undissolved drymedicament to the needle assembly 140, a medicament support 190 ispreferably provided between the end of the dry compartment 152 and theneedle assembly 140. The support 190 can serve to prevent blockage ofthe needle assembly 141 by preventing the dry medicament from enteringthe area surrounding the needle assembly 140 while permitting passage ofthe mixture of dissolved medicament and liquid injection solution. Thesupport 190 may be configured as described in U.S. ProvisionalApplication No. 60/238,448, which is herein incorporated by reference ina manner consistent with this disclosure. It is contemplated thatmultiple supports 190 may be located within the dry compartment 152. Theprovision of the supports 190 may also improve the laminar flow of theliquid injection solution through the dry medicament thereby improvingdissolution.

[0041] Further, a diaphragm assembly (not shown) may also be providedadjacent the medicament support 190, as known in the art. The diaphragmassembly acts to prevent the passage of the liquid injection solution tothe needle assembly 140 prior to activation of the actuator assembly120. More particularly, the diaphragm assembly will not rupture untileither the butt end of the needle assembly 140 ruptures the expandeddiaphragm or sufficient pressure builds in the dry compartment 160 torupture the diaphragm, again as known in the art.

[0042] As discussed above, the movement of the collet 122 causes theinjection needle 141 of the injection assembly 140 to advance andprotrude through the housing 110. As such, the injection of themedicament can be performed with a simple operation. In sum, the usersimply removes the end cap assembly 130, locates the injection end ofthe housing 110 adjacent the injection site, and presses the push button132. This operation automatically triggers the operation of the driveassembly or spring 250 to advance the collet 122 causing the liquidinjection solution located within the wet portion 151 to enter the dryportion 152 through the seal structure 160. The dissolved medicament isthen transmitted through the injection needle 141 to provide the userwith the necessary dose of medicament. The automatic injector 10 inaccordance with the present invention reduces the amount of timerequired to administer medicament compared to other wet/dry injectorsand eliminates the need for mixing by the user.

[0043] The seal structure 160 advantageously enables the manufacture ofa superior wet/dry auto injector with a complementary combination ofcomponents that are either known in the art of conventionalauto-injectors or are otherwise relatively simple to manufacture. Theseal structure 160 enables sufficient mixing of wet and dry medicamentcomponents without requiring manual shaking. This mixing action isenhanced by the filter or membrane 164. In a preferred embodiment, thefilter 164 is a supported, hydrophobic acrylic copolymer cast on anon-woven nylon support. Preferably, it is a FlouRepel treated membranefor superior oleophobicity/hydro-phobicity.

[0044] In another embodiment, clearly shown in FIG. 7, the automaticinjector cartridge includes a needle assembly 140 located within the dryportion 152. The needle assembly 140 extends within the dry portion 152to the sealing structure 180, described above in connection with FIGS.5A-5D. The sealing structure 180 separates the dry portion 152 from thewet portion 151. As shown in FIG. 7, the cartridge further includes aplunger 170 positioned therein. The plunger 170 is configured to engagethe collet 122 of the activation assembly 120. As clearly visible inFIG. 7, the cartridge includes a sheath 301. Like the sheath 202, thesheath 301 maintains the needle 141 in a sterile environment until itprojects from the end of the sheath 301 in response to activation of theactivation assembly 120. During operation, the needle assembly 140passes through the dry portion 152 as the wet medicament passes throughthe sealing structure 180.

[0045] In other embodiments (see FIGS. 8A and 8B), no inner plug 166 isprovided. Rather, the outer structure 180 is simply complemented by aseal membrane 226 that extends across the inner area defined by theinner surface of the outer structure. When the chamber 150 reaches theforward end of the housing during an injection operation, pressurizationof the wet compartment 151 causes the seal membrane 226 to rupture,thereby allowing the seal structure 160 to permit liquid to passtherethrough. In this embodiment, it may be desirable to provide theseal structure 160 with a pointed member 228 disposed adjacent to theseal membrane 226 to facilitate rupturing of the seal membrane uponpressurized expansion thereof during an injection operation. The member232 on which the pointed member 228 is mounted has a plurality ofpassages 234 that permits fluid to pass therethrough. Filter or membrane164 is preferably mounted distal to the passages 234 to present laminaror distributed flow to the dry medicament.

EXAMPLES

[0046] An injector according to the present invention was loaded withliquid injection solution and dry medicament and activated with thefollow results. Loaded Dispensed Operation Dry Powder Fluid Dry PowderFluid al Time Mg Ml % mg ml Secs. 531 2.7 94 497 2.3 4.0 557 2.7 93 5152.3 4.5 582 2.6 92 537 2.2 4.4

[0047] It will be apparent to those skilled in the art that variousmodifications and variations may be made without departing from thescope of the present invention. For example, it is contemplated that acover assembly, described for example in U.S. Pat. No. 5,295,965 (thedisclosure of which is specifically incorporated herein by reference)may be secured to the injection end of the housing 110 after deploymentof the medicament. Furthermore, the automatic injector may furtherinclude a nipple plunger assembly, as described for example in U.S. Pat.No. 5,465,727 (the disclosure of which is specifically incorporatedherein by reference).

[0048] In yet a further embodiment, the forward dry chamber 152 containsthe needle 141, as shown in FIG. 7. The needle 141 is forced through aforward plug stopper upon initial compression of the two chamber system.As known in the art, providing the needle in the forward chamberprovides improved longitudinal compactness of the design.

[0049] In yet another embodiment, a pre-filled syringe is provided withthe seal structure disposed between wet and dry components.

[0050] In further contemplated embodiments, the seal structure 160 canbe used in the same type of injector described herein, except ratherthan employing a dry (powder) medicament separated by a liquidcomponent, a first liquid medicament is separated from a second fluidcomponent by the seal structure 160. In yet another embodiment, the sealstructure 160 can be used in what is known in the art as a “needlelessinjector” where an injection can be made into a patient without a needleor cannula.

[0051] Thus, it is intended that the present invention covers themodifications and variations of the invention, provided they come withinthe scope of the appended claims and their equivalents.

What is claimed is:
 1. A separation assembly for a container forseparating a first component from a second component, wherein the firstcomponent is to be mixed with the second component in the container uponoccurrence of a predetermined operating condition, the separationassembly comprising: a generally cylindrical body that is constructedand arranged to be slidably supported within the container between theliquid component and the dry component, wherein the body includes a sealstructure constructed and arranged within the container between thefirst component and the second component, the seal structure having aninner seal member wherein the inner seal member being initially in asealing condition that maintains the first component sealed from thesecond component, the inner seal member being converted to a mixingcondition in response to the predetermined operating condition such thatthe first component flows through at least one flow path in the sealstructure to mix with the second component, wherein the body furtherincludes a flow distributing member disposed adjacent the seal structureto evenly distribute the first component into the second component uponoccurrence of the predetermined operating condition, whereby the sealstructure and the flow distributing member form a single unit.
 2. Theseparation assembly according to claim 1, wherein the flow distributingmember comprises a filter.
 3. The separation assembly according to claim1, wherein the seal structure comprises a sealing assembly having amovable plug.
 4. The separation assembly according to claim 3, whereinthe sealing assembly has an outer periphery that is constructed andarranged to form a peripheral seal with an interior wall of thecontainer.
 5. The separation assembly according to claim 1, wherein theseal structure incorporates a burstable membrane.